Forest, edge, and opening microclimate at Sicamous Creek

Abstract

The Sicamous Creek research site is 7 km east-southeast of Sicamous (50° 50' N, 119° 55' W) at an elevation of 1530-1830 m, on a northwest-facing slope. The Engelmann spruce-subalpine fir forest (ESSFwc2) is 22-27 m tall and canopy closure is about 50%. The climate at the site of the Sicamous Creek Silvicultural Systems Project is cool and moist with a mean annual air temperature of 1.2°C and an annual precipitation of 910 mm, about half of which occurs as snow.

The treatments monitored in this study were 0.1-, 1-, and 10-ha openings and mature forest. The base weather station was in a large opening with scattered regeneration adjacent to the experimental area. This study, in agreement with other studies, shows that most of the change in microclimate from forest to opening takes place within one tree height either side of the forest/opening edge. Openings of less than one tree height in diameter have a solar, wind, and thermal environment similar to that in the forest. Edge orientation has an effect, particularly for south-facing edges, where solar radiation can penetrate some distance into the forest for much of the day. Wind blowing directly into an edge penetrates farther into the forest than from other directions. The forest intercepts 20-30% of the precipitation. On sunny days, the forest air temperature near the ground is 2-4°C cooler than in the large openings. Near-surface daytime soil temperature is also 2-4°C cooler in the forest, while near-surface nighttime soil temperatures are similar.